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Choutka C, DeVorkin L, Go NE, Hou YCC, Moradian A, Morin GB, Gorski SM. Hsp83 loss suppresses proteasomal activity resulting in an upregulation of caspase-dependent compensatory autophagy. Autophagy 2017; 13:1573-1589. [PMID: 28806103 PMCID: PMC5612217 DOI: 10.1080/15548627.2017.1339004] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
The 2 main degradative pathways that contribute to proteostasis are the ubiquitin-proteasome system and autophagy but how they are molecularly coordinated is not well understood. Here, we demonstrate an essential role for an effector caspase in the activation of compensatory autophagy when proteasomal activity is compromised. Functional loss of Hsp83, the Drosophila ortholog of human HSP90 (heat shock protein 90), resulted in reduced proteasomal activity and elevated levels of the effector caspase Dcp-1. Surprisingly, genetic analyses showed that the caspase was not required for cell death in this context, but instead was essential for the ensuing compensatory autophagy, female fertility, and organism viability. The zymogen pro-Dcp-1 was found to interact with Hsp83 and undergo proteasomal regulation in an Hsp83-dependent manner. Our work not only reveals unappreciated roles for Hsp83 in proteasomal activity and regulation of Dcp-1, but identifies an effector caspase as a key regulatory factor for sustaining adaptation to cell stress in vivo.
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Affiliation(s)
- Courtney Choutka
- a Canada's Michael Smith Genome Sciences Centre , BC Cancer Agency , Vancouver , BC , Canada.,b Department of Molecular Biology and Biochemistry , Simon Fraser University , Burnaby , BC , Canada
| | - Lindsay DeVorkin
- a Canada's Michael Smith Genome Sciences Centre , BC Cancer Agency , Vancouver , BC , Canada.,b Department of Molecular Biology and Biochemistry , Simon Fraser University , Burnaby , BC , Canada
| | - Nancy Erro Go
- a Canada's Michael Smith Genome Sciences Centre , BC Cancer Agency , Vancouver , BC , Canada.,b Department of Molecular Biology and Biochemistry , Simon Fraser University , Burnaby , BC , Canada
| | - Ying-Chen Claire Hou
- a Canada's Michael Smith Genome Sciences Centre , BC Cancer Agency , Vancouver , BC , Canada
| | - Annie Moradian
- a Canada's Michael Smith Genome Sciences Centre , BC Cancer Agency , Vancouver , BC , Canada.,c Beckman Institute, California Institute of Technology , Pasadena , CA , USA
| | - Gregg B Morin
- a Canada's Michael Smith Genome Sciences Centre , BC Cancer Agency , Vancouver , BC , Canada.,d Department of Medical Genetics , University of British Columbia , Vancouver , BC , Canada
| | - Sharon M Gorski
- a Canada's Michael Smith Genome Sciences Centre , BC Cancer Agency , Vancouver , BC , Canada.,b Department of Molecular Biology and Biochemistry , Simon Fraser University , Burnaby , BC , Canada.,e Centre for Cell Biology, Development, and Disease , Simon Fraser University , Burnaby , BC , Canada
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Abstract
It has become evident that caspases function in nonapoptotic cellular processes in addition to the canonical role for caspases in apoptotic cell death. We recently demonstrated that the Drosophila effector caspase Dcp-1 localizes to the mitochondria and positively regulates starvation-induced autophagic flux during mid-oogenesis. Loss of Dcp-1 leads to elongation of the mitochondrial network, increased levels of the adenine nucleotide translocase sesB, increased ATP levels, and a reduction in autophagy. We found that sesB is a negative regulator of autophagic flux, and Dcp-1 interacts with sesB in a nonproteolytic manner to regulate its stability, uncovering a novel mechanism of mitochondrial associated, caspase-mediated regulation of autophagy in vivo.
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Affiliation(s)
- Lindsay DeVorkin
- The Genome Sciences Centre; BC Cancer Agency; Vancouver, BC Canada; Department of Molecular Biology and Biochemistry; Simon Fraser University; Burnaby, BC Canada
| | - Sharon M Gorski
- The Genome Sciences Centre; BC Cancer Agency; Vancouver, BC Canada; Department of Molecular Biology and Biochemistry; Simon Fraser University; Burnaby, BC Canada
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